The principal efforts of this project are aimed at demonstrating that a computerized infectious disease monitor can be used to improve the quality of patient care in a cost effective manner. We propose to carry out three studies. 1) Minimize the inappropriate use of prophylactic antibiotics. We will observe the use of prophylactic antibiotics a) preoperatively, b) immediately postoperatively and c) for the proper duration. We will then implement an intervention strategy with the computer prompting the pharmacists when inappropriate antibiotics are being used. The pharmacists will contact physicians and inform them of the inappropriate therapy. We will observe and evaluate the effect of this computer feedback method on physician behavior, costs and measures of quality of patient care. 2) Optimize the use of therapeutic antibioties. Studies have shown that 15 to 30% of patients are on ineffective antibiotics based on susceptibility results. We will review our data base for a one year period to assess the problem. Then we will alert the pharmacists who will contact the physicians and evaluate their response similar to the first study. 3) Computerized nosocomial infection surveillance - We will use the computer to alert the infectious disease staff of nosocomial infections. The infectious disease control team will then make recommendations. We will evaluate the effect these recommendations have on physician behavior, costs and measures on quality of patient care.